Sodium-cesium ionization detector

Abstract

Sodium-cesium detection systems and methods for the simultaneous detection of both sodium (Na) and cesium (Cs) in gas are provided. The detection systems include two non-identical ionization chambers each having an anode and a cathode that ionize Na and Cs in gas. Each ionization chamber generates a current proportional to the Na and Cs concentration and based on the current, Na concentration and Cs concentration in the gas is determined.

What is claimed is: 
     
       1. A detector comprising:
 a first ionization chamber having a first anode and a first cathode, the first anode having a first anode geometry; and 
 a second ionization chamber having a second anode and a second cathode, the second anode having a second anode geometry different from the first anode geometry. 
 
     
     
       2. The detector of  claim 1  further comprising:
 a data processor that generates a concentration of a first analyte from a first output from the first ionization chamber and a second output from the second ionization chamber. 
 
     
     
       3. The detector of  claim 2  wherein the first output is one of a first current between the first anode and the first cathode or a signal derived from the first current. 
     
     
       4. The detector of  claim 2  wherein the first analyte is one of cesium and sodium. 
     
     
       5. The detector of  claim 1  wherein the cathode of at least one of the first ionization chamber and the second ionization chamber is a tubular cathode such that the anode is positioned within the tubular cathode. 
     
     
       6. The detector of  claim 5  wherein the tubular cathode has a sidewall with at least one opening defined therein. 
     
     
       7. The detector of  claim 5  wherein at least one of the cathode and anode have at least a portion of insulation. 
     
     
       8. The detector of  claim 1  wherein at least one of the first anode and the second anode is a noble metal or alloy thereof. 
     
     
       9. The detector of  claim 1  further comprising:
 at least one third ionization chamber having a third anode and a third cathode, the third anode having a third anode geometry different from the first and second anode geometries. 
 
     
     
       10. The detector of  claim 1  wherein at least one of the first anode and the second anode is a coiled anode and the other anode is a straight anode. 
     
     
       11. A sodium-cesium detector comprising:
 a first ionization chamber having a heated, coiled anode within a tubular cathode and outputting a first current proportional to sodium and cesium ions flowing through the first ionization chamber; 
 a second ionization chamber having a heated, straight anode within a tubular cathode and outputting a second current proportional to sodium and cesium ions flowing through the second ionization chamber; and 
 a data processor outputting a sodium concentration and a cesium concentration based on the first current and the second current. 
 
     
     
       12. The sodium-cesium detector of  claim 11  wherein the first ionization chamber and the second ionization chamber are configured serially so that the sodium and cesium ions flow first through one of the two ionization chambers and then through the other. 
     
     
       13. The sodium-cesium detector of  claim 11  wherein the first ionization chamber and the second ionization chamber are configured in parallel so that a first portion of the sodium and cesium ions flow through the first ionization chamber and a second portion sodium and cesium ions flow through the second ionization chamber. 
     
     
       14. A method of monitoring a gas for two analytes comprising:
 flowing gas through a first ionization chamber, thereby creating a first ionization current that is a known first function, F 1 , of the concentration of a first analyte and a second analyte; 
 flowing gas through a second ionization chamber, thereby creating a second ionization current that is a known second function, F 2 , of the concentration of a first analyte and a second analyte; 
 analyzing the first and second currents to determine a concentration of the first and second analytes based on the first function, F 1 , and the second function, F 2 ; 
 comparing the concentration of at least one analyte to a threshold; and 
 generating a signal upon determination that the concentration of at least one analyte exceeds the threshold. 
 
     
     
       15. The method of  claim 14  wherein at least one of the first analyte and the second analyte is cesium and the other analyte is sodium. 
     
     
       16. The method of  claim 14  wherein the first ionization chamber and the second ionization chamber are configured serially so that flowing gas through the first ionization chamber is before flowing gas through the second ionization chamber. 
     
     
       17. The method of  claim 14  wherein the first ionization chamber and the second ionization chamber are configured in parallel so that flowing gas through the first ionization chamber is concurrent with flowing gas through the second ionization chamber. 
     
     
       18. The method of  claim 14  wherein generating a signal further comprises generating an alarm. 
     
     
       19. The method of  claim 14  wherein generating a signal further comprises controlling the flow of gas through the first and second ionization chambers. 
     
     
       20. The method of  claim 19  wherein controlling the flow of gas further comprises stopping the flow of gas. 
     
     
       21. A sodium-cooled nuclear reactor comprising:
 a reactor core; 
 a sodium coolant system; 
 a reactor control system; and 
 at least one sodium-cesium detector, each sodium-cesium detector having:
 a first ionization chamber having a heated, coiled anode within a tubular cathode and outputting a first current proportional to sodium and cesium ions flowing through the first ionization chamber; 
 a second ionization chamber having a heated, straight anode within a tubular cathode and outputting a second current proportional to sodium and cesium ions flowing through the second ionization chamber; and 
 a data processor outputting to the reactor control system a sodium concentration and a cesium concentration determined based on the first current and the second current.